[Help] Heeler Help

So I am the proud of owner of an insanely intelligent 1 year old blue heeler/australian cattle dog named Rango. Rango was raised around many other dogs, although they were only small canines. When she was around 7-8 months we introduced her to Maui, a gsd puppy who was the same age at the time. They played and had a grand old time, they continued to see eachother several times after that, on and off-leash, but always supervised. At 10 months old she suddenly became very dog aggressive, small dogs, big dogs, any other canine had her lashing out like she was rabid. She hasn't been spayed yet, but we do plan on having her spayed. We cant have her around Maui (or any other dog) without a muzzle or e-collar.

I feel awful for having to resort to the e-collar, though I hold nothing against the people who use these methods, what's effective for one dog may not be effective for another after all. Her behavioral issues do not stop there however, she gets antsy around strangers even going as far as to lunge, muzzle bump, and even growl at any stranger, she tries to chase after cars, lights (like flashlights, lazer pointers, etc.), fan blades, any loud noises, and small animals. For the most part I understand these behaviors, chasing after squirrels and birds is a pretty normal canine thing and after a quick recall she'll bounce right back to my side after all.

I feel some of it stems from her lack of exercise which is my fault, but we dont have many places to walk/exercise her currently, our yard is not fenced in, and we live near some pretty hazardous streets (her trying to lunge at cars even on on leash is a hassle). Not to mention the area we are in is populated with many other canines. Walking her has gone from enjoyable to a hassle. I have resorted to doing it only at night, which is incredibly dangerous given I'm rather small and also only 16. But I just cant find any other way to keep her from getting uppity about every little noise.

I have no idea the cause or reason, although I suspect anxiety, considering I do online school I'm with her 24/7, so she never has to leave my side or worry about me "disappearing", this has developed into separation anxiety. Anytime I leave her for more than an hour, (which I try not to do, but emergencies do come along) she will find something to destroy. Be it a pillow or clothing. And it's not like Rango doesnt listen or understand, she knows clearly when she has done something wrong, and she knows all sort of tricks, but I just cant seem to teach her how to stop these bad behaviors. So any tips or tricks?

(And sorry if I did something wrong, I'm very new to reddit.)